Performance analysis of small-scale power cycles for LNG physical exergy recovery

Abstract

Stricter air pollution regulations and emission controls have made the liquefied natural gas (LNG) a promising alternative fuel for marine transportation. LNG as a cryogenic fluid has large physical exergy (about 1000 kJ/kg), that can be partially recovered during regasification process in fuel systems of LNG-fuelled vessels. One of the ways of utilizing LNG physical exergy is to use evaporating LNG as a low-temperature heat sink to produce electric power in thermodynamic cycles, such as Organic Rankine Cycle (ORC). The efficiencies of major components of ORC systems, such as expanders or cryogenic pumps, depends largely on the power rating of the system, influencing the optimal parameters of the planned cycle. This research consists of performance analysis and thermodynamic optimization of the thermodynamic cycles for LNG exergy recovery in small-scale transportation systems.